It's not often that you get to take a swimming lesson from a box office idol.

ESTHER WILLIAMS: See if you can lift your elbow until you stretch that arm out straight. Oh, you're going to improve your stroke so much just this afternoon. You'll see.

SIMON: In 1999, we profiled Esther Williams, a former Southern California swim champ who looked so sensational in a bathing suit that studios invented a whole new movie genre for her, the aqua musical. Esther Williams died this week in Beverly Hills. She was 91. She starred in more than 20 films in the '40s and '5os, including "Neptune's Daughter," "Dangerous When Wet,"and "Million Dollar Mermaid."

The point of them all was to get Esther Williams under water, where she had a grace that beguiled audiences.

WILLIAMS: Water is very changeable. It's not a steady medium. You swim with somebody, that's why it's so sexy because hands just wander under water and all of a sudden - Peter Lawford, I'll never forget in "On an Island With You," he said how long as this been going on? Why did I miss this? And I said Peter, you're supposed to keep your hands to yourself. I'm not part of your stroke.

SIMON: And the medium has special requirements. How, for example, to keep your skin from puckering up like an elephant's knees and your hair from looking like a plate of angel hair pasta hovering in midair when you're filming under water for whole days? Over 20 years in films, Esther Williams had to swim through Busby Berkeley routines around thickets of coral and cables, swim in time with horses, Tarzan and Tom and Jerry, and never gasp for breath or betray the strain. She could never stop smiling.

WILLIAMS: All of these things done for a beautiful effect and nobody in the audience having any idea that you have accomplished the impossible.

SIMON: The day we visited, Ms. Williams gave her instructions dry from the deck of her pool, wearing white shorts, a blue top and white pumps. I was wearing a pair of red and white print swim trunks but I wouldn't be confused with, say, Ricardo Montalban, even when I asked for instructions on how to swim for the camera.

Let me try the Esther Williams part. Keep my head out of the water, right?

WILLIAMS: Yeah.

SIMON: I'm going to drown.

WILLIAMS: It's a powerhouse kick.

SIMON: Let me try it again.

WILLIAMS: You've got to be smooth. That's what makes it - and it's the stretch that makes it smooth.

(SOUNDBITE OF MUSIC)

SIMON: The great Esther Williams, who died this week at the age of 91.